Various objects can be transparent and have a top surface and at least one other side surface that is bevel (hereinafter—beveled side surface).
These objects can be semiconductor devices, Light Emitting Diodes, etc. FIGS. 1 and 2 illustrates a prior object 10 that has a trapezoid cross section—it includes a horizontal bottom surface 13, a horizontal top surface 11, a first beveled side surface 12 and a second beveled side surface 14. The horizontal bottom surface 13 is smaller than the top surface 11. The first beveled side surface 12 is oriented at 45 degrees in relation to the horizon and the second beveled side surface 14 is oriented at minus 45 degrees (−45) in relation to the horizon.
FIG. 1 illustrates the object 10 as having multiple elements 15, although it may have elements of different sizes and shapes. These elements 15 are expected to be seen at an image of the object—one or more element can reflect light although the object 10 may have elements that are not reflective. The first beveled side surface 12 has a top edge 18 that is parallel to an imaginary Y-axis and the second beveled side surface 14 has a top edge 19 that is parallel to the imaginary Y-axis.
Top illumination (bright field illumination) may be reflected back from the top and bottom horizontal surfaces 11 and 13 of the object and from elements of the object, enabling inspecting them. This is illustrates in FIG. 3—arrows 22 and 21 are non-limiting examples of multiple-reflected light signals—light signals that are reflected multiple times by multiple of beveled side surfaces of the multiple beveled side surfaces.
Arrows 22 illustrate impinging light signals that are reflected from the first beveled side surface 12 towards the second beveled side surface 14 and from the second beveled side surface 14 towards a sensor.
Arrows 21 illustrate impinging light signals that are reflected from the second beveled side surface 14 towards the first beveled side surface 12 and from the first beveled side surface 12 towards a sensor.
The multiple-reflected light signals can cause a disturbance in an image of the object—as illustrated in FIG. 4. This disturbance can appear as a bright glare in an image of the object—as illustrated in grey areas 31 and 33 of image 30 of FIG. 4. The image 30 also includes images 35 of object elements 15 and a white background image portion 32 that corresponds to the bottom surface 13.
This disturbance may saturate specific zones (such as areas 31 and 33) in the image 30 and even if not, it is a disturbance in the image 30 that deteriorates or the inspection quality or prevents inspection at all.
There is a growing need to provide improved methods for inspecting objects while suppressing the bright glare.